The present invention relates generally to conveyor belt cleaning systems employing scrapers and more particularly to an improved scraper tension control for such conveyor belt cleaning systems.
Heretofore, it has been known to use elongated scraper elements to forcibly engage and clean outer belt surfaces of an endless belt conveyor as the belt moves from a discharge pulley at an end of a run, for example. The scraper element or elements are usually spring-biased to compressively contact the belt surface and thereby insure constant removal of particulate matter adhered thereto. Such conveyor belts and scraper cleaners are commonly used in a wide variety of material handling operations, such as, for example, in coal mining, iron ore and copper mining, to mention only a few.
In such belt cleaning scrapers, it has been proposed to utilize various means in addition to compressive springs to insure that a constant scraper pressure or tension is applied to the outer underside surface of the belt to provide improved cleaning action Exemplary of such are the scraper devices is the manually adjustable, spring-biased scraper disclosed in U.S. Pat. No. 3,631,968 to Ward; the flexible scraper/pneumatic air cylinder assist arrangement disclosed in U.S. Pat. No. 4,269,301 to Gibbs; and the rigid scraper/pneumatic air cylinder biasing system disclosed in U.S. Pat. No. 4,402,394 to Stoll. A further hydraulic/pneumatic cylinder scraper biasing means is disclosed in U.S. Pat. No. 4,189,046 to Ward et al. These above prior systems employing pneumatic or hydraulic assists all suffer from a common shortcoming, namely, they each require a separate air compressor or hydraulic motor unit to drive the respective pneumatic or hydraulic scraper biasing equipment As such, these prior systems require electric, gasoline or diesel driven motors to power the equipment or must have motors which derive their power input from the running conveyor belt system. Needless to say, such auxiliary equipment is expensive to purchase, operate and maintain and is susceptible to field damage and breakdown in a rough field environment, such as, for example, in mining applications. Exposure to corrosive liquids such as acid mine waste water also shortens the service life of exposed precision components.
The present invention solves these problems by providing an improved conveyor belt cleaning system which employs constant torquing of the belt scrapers without the need for auxiliary hydraulic fluid motors or air compressors heretofore required in prior arrangements. The improved scraper control system of the present invention is particularly suited for use in mining operations such as coal mining wherein a pressurized source of mine waste water is readily available to energize the torquing device. The invention employs a limited number of moving parts including a central torquing activator unit constructed of a non-corrosive material which can withstand the acidic mine waste water with minimum maintenance and extended service life.